tsql to generate index creation text, then evaluate it - tsql

Question

I have a script that creates and populates a bunch of tables from data we receive as
text files. After loading the data into sql server 2008, I want to add indexes. The cut-and-paste-created script I'm using is shown below.
Is
there a way in TSQL to create a function that will generate and then
evaluate the DDL commands? The function would take parameters
of table name, column name(s) and clustered/not. If there would have
to be a separate function for 1 column/2 column indexes, I'd still
be interested.
I'm envisioning something like:
hypotheticalFunction('clustered', 'precCdaEarn', 'account', 'seq')
hypothericalFunction('nonClustered', 'flats', 'vendorAcct')
and that would check if an acct called "idx_acct_seq" exists on table
precCdaEarn, and drop it if so, then create it as clustered index. (dropping it just
in case i change the definition). And create/recreate a nonclustered index on dbo.flats named "idx_vendorAcct"
========= this is what have now using cut & paste, apologies for the erratic spacing ==============
IF EXISTS (Select 'X'
FROM sysindexes
WHERE id = (SELECT OBJECT_ID('precCdaEarn'))
and name = 'idx_account_seq')
DROP index precCdaEarn.idx_account_seq
Create nonclustered index idx_account_seq
ON precCdaEarn(account, seq)
;
IF EXISTS (Select 'X'
FROM sysindexes
WHERE id = (SELECT OBJECT_ID('acct'))
and name = 'idx_c_precAcct_precMod')
DROP index acct.idx_c_precAcct_precMod
CREATE CLUSTERED INDEX index idx_c_precAcct_precMod
ON acct(precAcct, precMod)

Answer 1

AFAIK you cannot create a function for this, but with a stored procedure it's no problems.
Something like:
IF(OBJECT_ID('PRC_CREATE_INDEX', N'P') IS NOT NULL)
DROP PROCEDURE PRC_CREATE_INDEX
GO
CREATE PROCEDURE dbo.PRC_CREATE_INDEX
(
-- Table name to add index to
#pTablename AS VARCHAR(120)
-- Index name to add/change
, #pIndexname AS VARCHAR(120)
-- UNIQUE, CLUSTERED or other definition
, #pNewIndexDef AS VARCHAR(255) = ''
-- Columns in index
, #pNewIndexCols AS VARCHAR(255)
-- Recreate even if same
, #pForceRecreate AS SMALLINT = 0
-- Additional columns for INCLUDE
, #pColumnsInclude AS VARCHAR(255) = ''
)
AS
------------------------------------
-- Variabels
------------------------------------
DECLARE #SQL_DROP AS NVARCHAR(1000)
, #SQL_CREATE AS NVARCHAR(1000)
, #retval AS INTEGER
, #rowcount AS INTEGER
DECLARE #oldDescription AS VARCHAR(255)
, #newUnique AS SMALLINT
, #newClustered AS SMALLINT
, #newIndexDef AS VARCHAR(255)
, #newDescription AS VARCHAR(255)
, #drop_index AS BIT
, #temp AS VARCHAR(MAX)
------------------------------------
-- Initiate
------------------------------------
SET XACT_ABORT ON
SET NOCOUNT ON
-- Table exists?
IF(OBJECT_ID(#pTablename) IS NULL)
BEGIN
PRINT 'Error: Table does not exist: ' + #pTablename +
' (' + 'creation of index ''' + #pTablename + '.' + #pIndexname + ''')'
RETURN (1)
END
-----------------------------------------------------------------------------------------------------
-- New index
-----------------------------------------------------------------------------------------------------
-- Initiate (Remove blanks, get unique/clustered info)
SELECT #newIndexDef = #pNewIndexDef
-- Remove NONCLUSTERED
, #newIndexDef = REPLACE(#newIndexDef, 'nonclustered', '')
-- CLUSTERED?
, #newClustered = CASE WHEN PATINDEX('%clustered%', LOWER(#newIndexDef)) > 0 THEN 1 ELSE 0 END
, #newIndexDef = REPLACE(#newIndexDef, 'clustered', '')
-- UNIQUE?
, #newUnique = CASE WHEN PATINDEX('%unique%', LOWER(#pNewIndexDef)) > 0 THEN 1 ELSE 0 END
, #newIndexDef = REPLACE(#newIndexDef, 'unique', '')
-- Remove blanks etc.
, #pNewIndexCols = REPLACE(#pNewIndexCols, ' DESC', '#DESC')
, #newIndexDef = REPLACE(#newIndexDef, ' ', '')
, #newIndexDef = REPLACE(#newIndexDef, ',', '')
, #pNewIndexCols = REPLACE(#pNewIndexCols, ' ', '')
, #pColumnsInclude = REPLACE(#pColumnsInclude, ' ', '')
-- Correct defintion?
IF LEN(#newIndexDef) > 0
BEGIN
RAISERROR ('Index defintion ''%s'' is incorrect for index ''%s.%s''!', 11, 11, #pNewIndexDef, #pTablename, #pIndexname)
RETURN (1)
END
IF #newClustered = 1 AND LEN(#pColumnsInclude) > 0
BEGIN
RAISERROR ('Cannot specify included columns for a clustered index (''%s.%s'')!', 11, 11, #pIndexname, #pTablename)
RETURN (1)
END
IF #pNewIndexCols LIKE '%#DESC%'
BEGIN
RAISERROR ('Descending sort direction not supported (''%s.%s'')!', 11, 11, #pTablename, #pIndexname)
RETURN (1)
END
IF #newClustered = 1 AND EXISTS
(
SELECT 1
FROM sys.indexes (NOLOCK)
WHERE object_id = OBJECT_ID(#pTablename, N'U')
AND name <> #pIndexname
AND type = 1 -- CLUSTERED
AND is_hypothetical = 0
)
BEGIN
SELECT #temp = name
FROM sys.indexes (NOLOCK)
WHERE object_id = OBJECT_ID(#pTablename, N'U')
AND name <> #pIndexname
AND type = 1 -- CLUSTERED
AND is_hypothetical = 0
RAISERROR ('Cannot add CLUSTERED index (''%s.%s'') - table already has a clustered index (''%s'')!', 11, 11, #pTablename, #pIndexname, #temp)
RETURN (1)
END
-- Prepare SQL
-- CREATE
SELECT #SQL_CREATE = ''
+ 'CREATE '
+ CASE WHEN #newUnique = 1 THEN 'UNIQUE ' ELSE '' END
+ CASE WHEN #newClustered = 1 THEN 'CLUSTERED ' ELSE 'NONCLUSTERED ' END
+ 'INDEX ' + #pIndexname + ' '
+ 'ON ' + #pTablename + ' '
+ '(' + #pNewIndexCols + ')'
+ CASE WHEN LEN(#pColumnsInclude) > 0 THEN ' INCLUDE (' + #pColumnsInclude + ')' ELSE '' END
-- Description
SELECT #newDescription = ''
+ CASE WHEN #newUnique = 1 THEN 'UNIQUE ' ELSE '' END
+ CASE WHEN #newClustered = 1 THEN 'CLUSTERED ' ELSE 'NONCLUSTERED ' END
+ '(' + #pNewIndexCols + ')'
+ CASE WHEN LEN(#pColumnsInclude) > 0 THEN ' INCLUDE (' + #pColumnsInclude + ')' ELSE '' END
-- DROP
SET #SQL_DROP = ''
+ 'DROP INDEX ' + #pTablename
+ '.' + #pIndexname
-----------------------------------------------------------------------------------------------------
-- Current index
-----------------------------------------------------------------------------------------------------
-- Initiate
SELECT #drop_index = 0
-- Get definition/description and check if recreation is needed
IF EXISTS
(
SELECT 1
FROM sys.indexes (NOLOCK)
WHERE object_id = OBJECT_ID(#pTablename, N'U')
AND name = #pIndexname
)
BEGIN
-- Description
SELECT #oldDescription = ''
+ CASE WHEN i.is_unique = 1 THEN 'UNIQUE ' ELSE '' END
+ CASE
WHEN i.type = 1 THEN 'CLUSTERED '
WHEN i.type = 2 THEN 'NONCLUSTERED '
ELSE '? '
END
+ '(' + STUFF(
(
SELECT ',' + COL_NAME(ic.object_id, ic.column_id)
FROM sys.index_columns ic (NOLOCK)
WHERE ic.object_id = i.object_id
AND ic.index_id = i.index_id
AND ic.is_included_column = 0
ORDER BY ic.key_ordinal
FOR XML PATH('')
)
, 1, 1, '') + ')'
+ ISNULL(' INCLUDE (' + STUFF(
(
SELECT ',' + COL_NAME(ic.object_id, ic.column_id)
FROM sys.index_columns ic (NOLOCK)
WHERE ic.object_id = i.object_id
AND ic.index_id = i.index_id
AND ic.is_included_column = 1
ORDER BY ic.index_column_id -- Or column_id???
FOR XML PATH('')
)
, 1, 1, '') + ')', '')
FROM sys.indexes i (NOLOCK)
WHERE i.object_id = OBJECT_ID(#pTablename, N'U')
AND i.name = #pIndexname
-- Exit?
-- If not changed and no force of recreation
IF #oldDescription = #newDescription
AND
#pForceRecreate = 0
BEGIN
RETURN 0
END
-- We should drop current index..
SET #drop_index = 1
END
-----------------------------------------------------------------------------------------------------
-- Execute SQL
-----------------------------------------------------------------------------------------------------
-- Exec
IF #drop_index = 1
EXEC sp_executesql #SQL_DROP
IF LEN(#pNewIndexCols) > 0
EXEC sp_executesql #SQL_CREATE
-- Message
IF LEN(#pNewIndexCols) > 0 AND #drop_index = 0
PRINT 'Created index ' + #pTablename + '.' + #pIndexname + ' (' + #newDescription + ')'
ELSE IF LEN(#pNewIndexCols) > 0 AND #drop_index = 1
PRINT 'Recreated index ' + #pTablename + '.' + #pIndexname + CHAR(10) +
' From: ' + #oldDescription + CHAR(10) +
' To: ' + #newDescription
-- Well, this will perhaps occur when and if this proc is changed...
ELSE IF #drop_index = 1
PRINT 'Removed index ' + #pTablename + '.' + #pIndexname + ' (' + #oldDescription + ')'
-----------------------------------------------------------------------------------------------------
-- Exit
-----------------------------------------------------------------------------------------------------
RETURN (0)
GO
Use it like:
EXEC dbo.PRC_CREATE_INDEX
#pTablename = 'someTable'
, #pIndexname = 'idx_someTable'
, #pNewIndexDef = 'CLUSTERED'
, #pNewIndexCols = 'some, columns, listed'